STAMFORD -- Stamford Hospital executives, board members and dignitaries will gather Tuesday for a ceremonial groundbreaking on what will become a shimmering new glass tower that will modernize aging facilities and serve as the hospital's largest expansion in its 117-year history.

The groundbreaking will formally kick off a $450 million construction project that has been discussed for nearly a decade when the hospital's board launched a strategic plan for the future.

Preparing the groundwork and placing the infrastructure needed for the new 11-story building has been taking place for nearly a year. So far, excavators have dug much of the western end of the foundation for a new larger hospital, including a lengthy channel for an underground tunnel linking the Central Utility Plant to the future building. The 33,500-square-foot utility plant is needed to support the power and other needs of the larger 600,000-square-foot facility.

On another section of the 30-acre campus, cranes are working to finish a parking area closer to Shelburne Road. All the work is part of a carefully orchestrated 15-phase plan devised to minimize disruptions at the existing facility.

"A primary responsibility will be communication between the job site and hospital on a daily basis about potential impacts to avoid disruption to clinical operations," said Stan Hunter, the project's executive director.

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Construction timeline:Aug. 2011: Crews began demolishing homes along Shelburne Road to create space for future parking areas needed for the project and the new hospital;Aug. 2012: The hospital begins construction on the central utility plant behind the hospital which is expected to be completed by December of this year. Construction of new parking spaces on the east end of the campus also takes place to prepare for construction;Sept. 2012: Construction begins on new joint entrance courtyard for the Whittingham Pavilion and Bennett Cancer Center in anticipation of shutdown of main Bennett Cancer Center entrance off of Shelburne Road to accommodate main construction;April 2013: The hospital opens a newly built joint entrance and courtyard for the Whittingham Pavilion and Bennett Cancer Center located off West Broad Street next to the Jean S. Rich Office Building and institutes free valet parking for patients and visitors. Both facilities are still accessible through the main hospital building's entrance facing Shelburne Road;May 2013: The hospital breaks ground on the new hospital building, and is currently excavating the foundation for the facility.;Aug. 2012: A new parking lot of approximately 275 spaces for hospital staff is scheduled for completion;Spring 2016: New hospital scheduled to open.

Hospital officials had considered building a new facility in three phases over the next 10 to 15 years, but opted to expedite construction to complete the project by 2016 to take advantage of favorable interest rates expected to yield $125 million in savings.

The building, which will be located on the existing parking lot south of the Whittingham Pavilion, is meant to serve as a state-of-the-art replacement for the hospital's aging main building on Merrell Avenue. The new building will feature significantly larger patient rooms. Presently, rooms inside the main building average around 130 square feet. The new suites will be 244 square feet and will be private, allowing for easier visitation by relatives.

The larger building will also allow the reconfiguration of space to centralize the hospital's Heart & Vascular Institute which is currently spread through the existing hospital, and accommodate a larger critical care unit which will grow from 16 to 24 beds in size.

The hospital's pediatric unit will be moved to the Whittingham Pavilion, putting the hospital's Neonatal care unit under the same roof, according to the plan.

Last month the hospital opened a new joint entrance into the Whittingham Pavilion and Bennett Cancer Center that will be shared by patients of both facilities for the duration of the project. The former entrance to the Bennett and the Whittingham Pavilion will be inside the construction site.

Hospital spokesman Scott Orstad said patients of those facilities have been notified by letter about the changed access to the campus to help minimize inconvenience or confusion while coming to the campus during the work.

Since last year, the hospital has been putting in place new parking lots, including one that will be finished on the former site of Vidal Court, a city housing complex, to accommodate patients. Many hospital employees have been diverted to park in the UConn Stamford parking garage, Orstad said.

"We've been working almost a year building parking lots and decommissioning other lots to get ready," Mike Smeriglio, executive director of facilities for the hospital, said.

During construction, the project's contractor New Haven-based Skanska and hospital executives running the project will coordinate weekly to anticipate at least two months ahead any activities that will impact patients, staff and visitors, according to the project managers.

Expected changes like noise from excavations, interior work and parking lot shifts will be shared with the hospital's communication staff who will use mailings to patients and staff, increased signage around campus, and information posted on stamfordhospital.org to provide notice.

"There are a lot of logistics that go into keeping the hospital functional and to make sure we're not impacting clinical services," Smeriglio said.

To help guide the project's contractor and ensure pipes, wiring, and other fixtures of the new building are completed precisely, Smeriglio, Hunter, and Skanska officials are using Building Infrastructure Management software which allows them to review a virtual model of the building via computer to cross check ongoing work.

"We can look at different parts of the building this way before they are built and make sure that it's going right," Smeriglio said.